Information recorder information recording method optical recording medium and information processor

ABSTRACT

Copyright protection information, which is recorded on an optical recording medium, is made not to be easily cracked, so that the profits of copyright owners are protected.  
     Signals based on a plurality of sequences obtained by scrambling copyright protection information SA by using a plurality of binary sequences are recorded in a predetermined area of an optical recording medium ( 2 ). Since the copyright protection information SA cannot be decrypted as long as the plurality of binary sequences used for scrambling are not known, an encryption process can be performed by using the information as a key. Furthermore, during playback, the copyright protection information SA is decrypted by performing a correlation computation with the played back signal by using a plurality of binary sequences, which are the same as those used for scrambling the data during the recording of the copyright protection information SA. Then, the encryption performed on the recorded information is unscrambled using the information.

TECHNICAL FIELD

The present invention relates to technology for effectively protectingthe profits of copyright owners with regard to authored works in whichcontent data is recorded on a recording medium.

BACKGROUND ART

Various kinds of devices using optical recording media, for example,disc apparatuses for music purposes using a disc-shaped recording mediumhaving a diameter of 64 mm can simply and easily copy music data fromvarious content while preventing the deterioration of the sound quality,and thus they have been rapidly becoming popular in recent years. Thatis, in this type of apparatus, it is possible to record musicinformation distributed by using a network communication such as theInternet to a recordable disc and to test-listen it, or it is possibleto record music information of a borrowed compact disk (CD) to a discand to test-listen it. Furthermore, by performing a conversion fromdigital signals into analog signals, music data recorded on another disccan be copied to another disc.

However, whereas such simple and easy copying can considerably increasethe convenience for a user, there is a risk that the profits ofcopyright owners who create the music may be lost. For this reason, forexample, in organizations and forums, such as RIAA (Recording IndustryAssociation of America), SDMI (Secure Digital Music Initiative), andCPTWG (Copy Protection Technical Working Group), various techniques havebeen considered for the purpose of protecting the profits of copyrightowners.

As one of such techniques, a method in which music information isencrypted using unique copyright protection information and the hiddeninformation is recorded on a recording medium has been proposed. Thatis, according to this method, when music information is copied ontoanother recording medium, since the copyright protection informationdiffers in the recording medium, the encryption applied to the originalrecording information cannot be unscrambled or becomes difficult tounscramble. As a result of the above, unlimited copies are preventedfrom being made so as to protect the profits of copyright owners.

As such methods for recording copyright protection information, forexample, a method in which a sector to which access by a user isdifficult is provided on a disc and copyright protection information isrecorded on this sector, a method in which a reflection film is partlyremoved with respect to the recording of main data by pit sequences andcopyright protection information is recorded in the form of bar codes(International Publication 97/14144 pamphlet), and other methods havebeen proposed.

The conventional methods are not sufficient in practical terms from theviewpoint of effectively protecting the profits of copyright owners, andillegal activity (copying, etc.) based on decrypted copyright protectioninformation becomes a problem.

For example, in a method in which a sector to which access by a user isdifficult is provided on a disc and copyright protection information isrecorded on the disc, whereas the copyright protection information canbe recorded relatively simply and easily, there is a problem in that thecopyright protection information is likely to be copied illegally.

Furthermore, in the method in which a reflection film is partly removedand copyright protection information is recorded in the form of barcodes, when the copyright protection information is found by reading thebar codes using a microscope, there is the possibility that an illegalcopy is made, and there is a problem in that so-called pirated versionscannot be completely prevented.

The present invention has been made in view of the above points. Anobject of the present invention is to make copyright protectioninformation not to be easily cracked so as to protect the profits ofcopyright owners.

DISCLOSURE OF INVENTION

In order to solve the above-described problems, the informationrecording apparatus and the information recording method according tothe present invention record a signal based on a plurality of sequences,which are obtained by scrambling digital information for protectingcopyright by using a plurality of binary sequences.

The optical recording medium according to the present invention hasrecorded thereon a signal based on a plurality of sequences in whichdigital information is scrambled to protect copyright using a pluralityof binary sequences.

Therefore, according to these aspects of the present invention, thedigital information for protecting copyright, which is recorded on therecording medium, has a form of being irregularly changed as a result ofbeing scrambled in accordance with a plurality of binary sequences. As aresult, it is difficult to analyze the digital information forprotecting copyright as long as the plurality of binary sequences usedfor scrambling are not known.

The information recording apparatus according to the present inventionreconstructs digital information for protecting copyright by performinga correlation computation between a binary sequence and a played backsignal associated with the optical recording medium by using the sameplurality of binary sequences as those used for scrambling theinformation when the digital information for protecting copyright isrecorded.

Therefore, according to the present invention, digital information forprotecting copyright, which is recorded on the optical recording medium,can be reliably detected. Moreover, since, to reconstruct the digitalinformation for protecting copyright, the plurality of binary sequences,which are used when the digital information is recorded, are required,it is possible to prevent the digital information for protectingcopyright from being illegally decrypted. That is, since the digitalinformation for protecting copyright is recorded by a signal thatchanges according to the plurality of binary sequences, it is difficultto analyze the digital information for protecting copyright as long asthe plurality of binary sequences used for recording are not known.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the overview of steps of manufacturing an opticalrecording medium according to the present invention.

FIG. 2 shows a master disc of the optical recording medium according tothe present invention.

FIG. 3 is a configuration view showing an example of a master discexposure apparatus for the optical recording medium according to thepresent invention.

FIG. 4 is a block diagram showing an example of the configuration of amodulation circuit in the master disc exposure apparatus of FIG. 3.

FIG. 5 is a timing chart illustrating the operation of the modulationcircuit shown in FIG. 4.

FIG. 6 is an illustration schematically showing a state in whichcopyright protection information is recorded as a groove wobble in arecording medium.

FIG. 7 is a block diagram showing as an example a modulation circuithaving a configuration differing from that of FIG. 4.

FIG. 8 is an illustration showing the overview of a recording andplayback system in the present invention.

FIG. 9 is a block diagram showing an example of the configuration of aninformation processing apparatus using the optical recording mediumaccording to the present invention.

FIG. 10 is a block diagram showing an example of the configuration of asecond decryption circuit (decryption circuit for copyright protectioninformation) shown in FIG. 9.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to an information recording apparatus fora recording medium (for example, a recording apparatus for an opticalrecording medium) and a recording method, and an information processingapparatus using a recording medium (a recording and playback apparatus,etc.). For example, the present invention can be applied widely to asystem such as a recordable and playable disc (MD) for music uses and adigital video recorder (DVR) capable of recording and playing back videoinformation. In the present invention, to effectively protect theprofits of copyright owners, the bits of copyright protectioninformation regarding copyright protection are each scrambled by aplurality of binary sequences generated at a predetermined timing, andthe signals of the plurality of sequences generated by scrambling arerecorded on a recording medium.

Examples of a data recording form associated with the optical recordingmedium include an information recording method using light radiation,such as a laser beam, and an information recording method usingelectronic-ray radiation (regarded as the likeliest as the nextgeneration recording method).

FIG. 1 illustrates the steps of manufacturing an optical recordingmedium according to the present invention.

Regarding an optical recording medium, the recording form, a recordingmedium material, and a shape thereof do not matter. In the following, adescription is given by using a disc for music uses having a diameter of64 mm as a disc-shaped recording medium (hereinafter referred to simplyas a “disc”). This disc is produced in such a manner that a recordingfilm, a protection film, etc., are formed on optical disc substrates,which are manufactured in duplicates in mass production using a stamper.Furthermore, in this example, it is assumed that discs are sold to usersafter copyright protection information (hereinafter referred to as “SA”)before shipment from the factory is recorded in advance on all thediscs, and the copyright protection information SA is recorded as wobble(meandering) information of a groove on the disc.

Here, the “copyright protection information” means information (digitalinformation) for protecting copyright, which is associated with contentdata to be recorded on the recording medium. For example, as will bedescribed later, the copyright protection information is used as keyinformation for encryption (this is not limited to an encryption processin a narrow sense, but includes a scrambling process). Not being limitedto this, usage does not matter, for example, the copyright protectioninformation may be used as copying control information for prohibitingor limiting illegal copying.

In the example shown in FIG. 1, an information recording apparatus(optical recording apparatus) 1 includes a copyright information source1 a, an address information source 1 b, and a cutting machine (masterdisc exposure apparatus) 1 c.

The copyright protection information SA output from the copyrightinformation source 1 a and an address signal output from the addressinformation source 1 b using an address format signal generation circuitare supplied to the cutting machine 1 c. The cutting machine 1 cgenerates an optical modulation signal by performing signal processingon the copyright protection information SA, as will be described later,and radiates a recording laser beam modulated in accordance with theoptical modulation signal onto an optical master disc 200, causing thecopyright protection information SA to be recorded as a groove wobble inthe inner region of the optical master disc 200.

The recording of the copyright protection information by the cuttingmachine 1 c is performed in a copyright information recording area 200Ain the inner region of the disc (see FIG. 2). The reason for this isthat, in an ordinary optical disc, signal recording is performed in sucha manner that reading of information proceeds from the inner regiontoward the outer region. That is, since the copyright protectioninformation needs to be completely reproduced before information such ascontent is played back from a disc or before information is recorded onthe disc, the recording of the copyright protection information at aposition of the inner region of the disc is often more convenient. Ofcourse, even in the form in which recording is performed in the outerregion, an intermediate region, etc., of the disc, no particular problemis posed other than the access time. Furthermore, not being limited toone place of the disc, the copyright protection information may berecorded at a plurality of positions of the disc by considering a discmanufacturing error and the occurrence of a scratch, etc., due to use(however, in either cases, it is required that, which position of thedisc the copyright protection information is recorded be clearlyspecified, or the position information of the copyright protectioninformation be obtained using some kind of means).

The cutting machine 1 c records address information and information of agroove for tracking in a user data recording area 200B even if the laserbeam moves to the outer region of the copyright information recordingarea 200A. The optical master disc 200, on the entire surface of whichthe exposure and recording are performed in this manner, is developed,and thereafter, it is formed as a stamper 201 after undergoing a platingprocess. The stamper 201 is mounted in an injection molding machine, anddisc substrates 202, which are duplicated in mass production, areproduced.

Then, a recording film (a magneto-optical film or a phase change film)is deposited on the disc substrate 202 by using a sputtering apparatus,etc.

In the manner described above, the disc substrate 202 such that thecopyright protection information SA is recorded in the copyrightinformation recording area in the inner region of the disc is finallycoated with a protection film, completing an optical recording medium 2(in this example, a music disc), and this is passed to a user. Since thedata recorded on the disc is recorded after it is encrypted inaccordance with the copyright protection information SA, a general userunscrambles the encryption in accordance with the copyright protectioninformation recorded in the copyright information recording area withinthe disc in order to play back data or records information encrypted inaccordance with the copyright protection information on the disc (thedetails will be described later).

FIG. 3 shows the essential portion of an example of the configuration ofthe cutting machine 1 c.

The cutting machine 1 c includes a driving source and mechanism, androtation control means 3 for rotating the optical master disc 200.

The optical master disc 200 is rotationally driven by a spindle motor,which is a driving source 4. In the bottom part within the spindlemotor, a signal generator (FG) 5 is provided, so that an FG signal(detection signal) whose signal level rises for each predeterminedrotational angle is output.

A spindle servo control section 6 performs the driving control of thespindle motor so that the frequency of the FG signal supplied from thespindle motor becomes a predetermined frequency. This causes the opticalmaster disc 200 to be rotationally driven at a predetermined number ofrotations.

An optical radiation system 7 for the optical master disc 200 includes arecording light source 8, a light modulator 9, and optical devices suchas a mirror 10 and an objective lens 11.

In this example, a laser light source (recording laser) is used as therecording light source 8, and a laser beam L1 is emitted to the lightmodulator 9. For the recording laser, for example, a gas laser is used.

The light modulator 9 is formed using an acousto-optical deflector,etc., and causes the traveling direction of the laser beam L1 from therecording laser to change in accordance with an optical modulationsignal (denoted as an “SD”) and emits this beam as a laser beam L2.

The mirror 10 is provided to change the optical path of the laser beamL2 and causes the beam light to be reflected toward the optical masterdisc 200. Then, the objective lens 11 collects the light reflected fromthe mirror 10 onto the recording surface of the optical master disc 200.The change in the traveling direction of the laser beam L2, which iscollected by the objective lens 11 in this manner, is replaced with theposition displacement on the recording surface of the optical masterdisc 200, and exposure is performed. The optical-system forming devicesincluding the mirror 10 and the objective lens 11 are moved as desiredalong the radial direction of the disc in synchronization with therotation of the optical master disc 200 by a sled mechanism (movementmechanism) (not shown).

By displacing the light collection position of the laser beam L2, forexample, from the inner region toward the outer region in the radialdirection of the optical master disc 200, tracks can be formed in aspiral shape on the optical master disc 200. In the copyrightinformation recording area 200A shown in FIG. 2, a groove on whichwobbling (for example, meandering) corresponding to both the copyrightprotection information SA and the address information is performed isformed on the tracks within the area. Furthermore, in the user datarecording area 200B shown in FIG. 2, a groove in which the addressinformation is recorded is formed.

The copyright protection information SA supplied from the copyrightinformation source 1 a and the information from the address informationsource 1 b are processed in a signal processing section 12.

The copyright protection information SA is supplied to a modulationmeans (modulation circuit) 13, where modulation (to be described later)is performed on the copyright protection information SA in order togenerate a modulation signal (hereinafter referred to as a “copyrightmodulation signal” and denoted as an “SX”) by referring to the addresssignal (hereinafter denoted as an “SZ”) supplied from the addressinformation source 1 b through a modulation means (modulation circuit)14, and this signal is supplied to superposition means 15.

The signal from the address information source 1 b contains addressinformation required for positioning and various kinds of formatinformation, and the signal is supplied to the modulation means 14having a low-pass filter. The modulation means 14 is formed using anaddress format signal generation circuit and so on. The modulation means14 attenuates a signal of high frequency components contained in theinput signal so that only low frequency components required as addressinformation and format information are transmitted to generate theaddress signal SZ, and supplies the signal to the modulation means 13and the superposition means 15. During the playback of the signalrecorded on the recording medium, it is necessary to separate themodulation signal by the modulation means 13 from the modulation signalby the modulation means 14. In this example, in order that frequencyseparation be possible, in the modulation means 14, frequency modulationis used (a process for generating and inserting a synchronization signalrequired when the address information is played back is also included.).

The superposition means 15 superposes the respective modulation signalsobtained by the modulation means 13 and 14. For example, the copyrightmodulation signal SX supplied from the modulation means 13 and theaddress signal SZ supplied from the modulation means 14 are addedtogether, and the added result is output as the optical modulationsignal SD to the optical modulator 9.

Although not shown in the figure, the superposition means 15 includesthe components described below.

-   -   Frequency adjusting means for adjusting the frequency components        of the modulation signal SX or SZ, or both the modulation        signals.    -   Addition means for adding modulation signals (SX, SZ), which are        output through the frequency adjusting means.

In the frequency adjusting means, for example, adjustments are performedso that the frequency associated with one of the modulation signals is“f” hertz or higher and the frequency associated with the othermodulation signal is lower than. “f” hertz. In order to convert thefrequency, the signal (original signal) having a frequency of “a” hertzis multiplied by a sine wave having a frequency of “b” hertz. As aresult, since signal components of a sum frequency (a+b) and adifference frequency (a−b) are obtained, desired signal components areobtained by using an appropriate high-pass filter (HPF) and low-passfilter (LPF). If the original signal has a desired frequencydistribution from the beginning, such a process needs not to beperformed.

Furthermore, at the stage before the addition by the addition means,since it is assumed that each signal is separated in frequency, byadding the two signals, frequency multiplexing is performed. That is,after the modulation signals SX and SZ are frequency multiplexed, thesignal is finally recorded on the optical recording medium.

From the viewpoint of secrecy, generally speaking, CDMA (Code DivisionMultiple Access) is more advantageous than frequency multiplexing, butfrequency multiplexing is preferred from the viewpoint of simplificationof the circuit configuration.

A control section 16 formed using a CPU (Central Processing Unit), amemory, and so on centrally controls the entire system. For example, thecontrol section 16 supplies timing information and control informationnecessary for the circuit sections which form the modulation means 14and so on by referring to the position at which exposure is beingperformed on the optical master disc 200 (the radiation position of thelaser light in the radial direction of the disc).

The copyright protection information SA is used as, for example, keyinformation for encryption, which is used when the user records data onthe completed disc, and any desired random number can be used therefor.In another usage, SA can be used as information for specifying themanufacturing source when an illegal disc is distributed in the market.For example, by using, as SA, the apparatus number unique to the cuttingmachine, information associated with the manufacturing factory, andinformation such as the manufacturing year and date, necessary data maybe recorded on the disc.

In this example, in order to prevent the complexity, the signal line ofthe copyright protection information SA, which extends from thecopyright information source 1 a toward the modulation means 13, isindicated by one thick line. However, the copyright protectioninformation SA generally has information of a plurality of bits (forexample, in the description to be given later, since SA is formed as4-bit information, it is formed by four signal lines in the figure). Ofcourse, an increased amount of information by increasing the number ofbits is preferable in that a larger number of pieces of information canbe recorded.

In the following, the configuration and the operation timing of themodulation means 13 are described with reference to FIGS. 4 and 5. FIG.4 is a block diagram showing an example of the configuration of acircuit. FIG. 5 is an operation illustration including timing charts.

The address signal SZ input to the modulation means 13 is sent to a PLL(phase-locked loop) circuit 17 and a timing generator 18.

The PLL circuit 17 generates a channel clock “CK” (see FIG. 5(A))synchronized with the address signal SZ, and supplies the clock to thesections of the circuit.

The timing generator 18 detects a synchronization signal contained inthe address signal SZ and counts the channel clock “CK” at apredetermined timing, thereby generating an initialization pulse “SY”(see FIG. 5(B)). As shown in FIG. 5, this initialization pulse “SY” is apulse that indicates a logic value “1” at one clock width (for oneperiod of CK) (in FIG. 5, the initialization pulse SY for only one pulseis shown, but in practice, the initialization pulse SY is repeatedlygenerated at a predetermined period). Furthermore, the initializationpulse SY is used to initialize M-sequence generation circuits (19A to19D) (to be described later).

As binary-sequence generation means 19 for generating a plurality ofbinary sequences at a predetermined timing, in this example, M-sequencegeneration circuits 19A, 19B, 19C, and 19D are used. Here, the“predetermined timing” means a timing based on synchronization signaldetection, as will be described later. Furthermore, for a plurality ofrandom-number sequences, since the sequences are preferably in anorthogonal relationship (that is, the relationship that thecross-correlation is zero) or close to that relationship, an M sequence(Maximal Length Sequence) is used as a binary sequence. The M sequenceis a random-number sequence having a specific period, from whichrandom-number sequences having no cross-correlation are obtained by anumber corresponding to the sequence length. Furthermore, apseudo-random number can be obtained by a relatively simple circuitconfiguration. The number of the M-sequence generation circuitscorresponds to the number of bits associated with the copyrightprotection information SA (4 in this example).

When a binary sequence other than the M sequence is used, it isnecessary that the same signal (the signal of a pseudo-random numbersequence) be always generated repeatedly starting from theinitialization time (the position at which the synchronization signal isdetected). Then, during playback, it is required that the signalsequence can be generated at the same timing as that during recording(that is, the requirement is that the signal sequence for scrambling beknown in advance or the reproduction method be known). Examples thereofinclude a method of making the cross-correlation completely zero byusing a signal sequence of a sine wave and a cosine wave, whosefrequencies differ from each other. However, in this method, a specificfrequency is assigned to each bit associated with the information, andstrong frequency characteristics are given. Consequently, for example,in the case of an optical disc, there is a risk that an influence due tothe degree of the inclination of the disc during playback, the change inthe shape of a reading laser spot, etc., affects the change of thefrequency characteristics of a read signal (played back signal) (theinformation of a particular bit cannot be correctly detected, etc.).Therefore, in order to avoid such problems, it is preferable that thefrequency space be uniformly used for each bit by using a pseudo-randomnumber such as an M sequence. As a result, even if specific frequencycomponents slightly vary during playback, the load involved with thevariation can be uniquely distributed over all the bits rather than onspecific bits.

The M-sequence generation circuits 19A to 19D generate pseudo-randomnumber sequences, which differ from each other (hereinafter denoted asM1, M2, M3, and M4), each time the channel clock “CK” changes from a lowlevel to a high level, and outputs individual sequence data to digitalmultiplication circuits 20A to 20D correspondingly. That is, the signaloutput from the M-sequence generation circuit 19 x (x indicates one ofA, B, C, and D) is sent to the digital multiplication circuit 20 x(xindicates one of A, B, C, and D).

The digital multiplication circuits 20A to 20D constitute computationmeans 20 for outputting a computation result of a plurality of bitsassociated with the copyright protection information SA (digitalinformation) and a plurality of binary sequences by the binary-sequencegeneration means 19.

In this example, the pseudo-random number sequences M1 to M4 are Msequences that change in units of the channel clock CK, and theM-sequence generation circuits 19A to 19D are initialized in accordancewith the initialization pulse “SY” from the timing generator 18. In anexample, the pseudo-random number sequence M1 is shown in FIG. 5(E), thepseudo-random number sequence M2 is shown in FIG. 5(F), thepseudo-random number sequence M3 is shown in FIG. 5(G), and thepseudo-random number sequence M4 is shown in FIG. 5(H). For thepseudo-random number sequences M1 to M4, for example, the same Msequences each having a different initial value may be used.

The digital multiplication circuits 20A to 20D digitally multiply thepseudo-random number sequences M1 to M4 by the bits (b0 to b3) of thecopyright protection information SA. That is, the digital multiplicationcircuit 20A computes the exclusive OR of the pseudo-random numbersequence M1 and the lowest bit “b0” of the copyright protectioninformation SA, and outputs the computation result to selection means(data selector) 21. In a similar manner, the other digitalmultiplication circuits 20B to 20D perform identical computations withrespect to the pseudo-random number sequences M2 to M4 and the bits b1to b3 of the copyright protection information SA, and outputs thecomputation result to the selection means 21. That is, the exclusive ORof the pseudo-random number sequence M2 and the bit “b1” of thecopyright protection information SA is calculated in the digitalmultiplication circuit 20B; the exclusive OR of the pseudo-random numbersequence M3 and the bit “b2” of the copyright protection information SAis calculated in the digital multiplication circuit 20C; and theexclusive OR of the pseudo-random number sequence M4 and the highest bit“b3” of the copyright protection information SA is calculated in thedigital multiplication circuit 20D. Then, all the computation resultsare sent to the selection means 21.

For the computation performed in the computation means 20, exclusive ORor its negative logic computation (logical NOT of exclusive OR) is mostappropriate. The reason for this is a problem that, in computations suchas logical sum (OR) and logical product (AND), information cannot becorrectly detected when the information (SA) (to be described later) isreconstructed or the detection takes a long time.

In this example, the selection means (data selector) 21 together withrandom number generation means 22 constitutes integration means 23, andgenerates an integration signal by integrating a plurality ofcomputation results obtained by the computation means 20.

A 2-bit random number generated by a circuit which forms the randomnumber generation means 22 (random number generation circuit) issupplied to the selection means 21, and the selection means 21 selectsone of the computation results from the computation means 20 inaccordance with the value of the random number.

The random number generation circuit is a circuit for generating a truerandom number or a pseudo-random number. It is preferable that the truerandom number be generated, and the advantage that the secrecy isincreased by an amount corresponding to that the sequence does not havea periodicity. However, from the viewpoint of the simplification of theconfiguration, a pseudo-random number generation circuit can be usedinstead. Examples of the circuit configuration for generating a randomnumber include a circuit for amplifying electrical noise and forperforming digitization (A/D conversion) thereon. Furthermore, examplesof the circuit configurations for generating a pseudo-random numberinclude a configuration in which data of a random-number sequence, whichis generated using a signal generation circuit for an M sequence or arandom number generation function provided as a library function in acomputer is prestored in storage means such as a ROM (Read Only Memory),and a random number is generated by reference to the data. Examples ofthe advantages of using the pseudo-random number sequence include theitems described below.

Capability of generating a stable random-number sequence with arelatively simple circuit (a random number, which is deviated due tosome conditions, is not generated, and the reliability ofcharacteristics is ensured.)

Can be easily formed as a digital circuit, can be easily contained in asingle chip, and the risk that the random-number sequence is revealed byexternal analysis is low.

The random number generated by the random number generation means 22changes in units of the channel clock CK and takes one of the values ofthe four numerals “0, 1, 2, and 3”. The selection means 21 selects oneof the four inputs supplied from the digital multiplication circuits 20Ato 20D in accordance with the 2-bit random number supplied from therandom number generation means 22, and outputs the result to the dataselector 24 at a subsequent stage. For example, when the value of therandom number supplied from the random number generation means 22 is“0”, the output of the digital multiplication circuit 20A is selected inthe selection means 21. In the following, similarly, the selection ofthe output of the digital multiplication circuit in accordance with therandom number value is performed as described below.

-   -   When the random number value is “1”==>the output of the digital        multiplication circuit 20B is selected.    -   When the random number value is “2”==>the output of the digital        multiplication circuit 20C is selected.    -   When the random number value is “3”==>the output of the digital        multiplication circuit 20D is selected.

The output of the digital multiplication circuit selected by theselection means 21 is output to the data selector 24, where a selectionis performed with respect to another signal.

A synchronization pattern signal (see FIG. 5(D)) from a synchronizationpattern generation circuit 25 is supplied to the data selector 24. Thesynchronization pattern generation circuit 25 is provided to generate asynchronization pattern signal in accordance with a signal from thetiming generator 18. For example, as shown in FIG. 5, a synchronizationpattern signal at the logic (positive logic) level of “11011” isgenerated in synchronization with (the rise of) the initialization pulse“SY” supplied from the timing generator 18, and this signal is output tothe data selector 24.

Furthermore, a signal from the timing generator 18 (hereinafter referredto as a “copyright synchronization pattern selection signal”, anddenoted as “ST”) is supplied to the data selector 24. As shown in FIG.5(C), the copyright synchronization pattern selection signal ST rises atthe same time as the rise of the initialization pulse SY and whose logiclevel (logical value) becomes “1” for only the period of a 5-clock (CK)width.

In the data selector 24, one of the output signal of the synchronizationpattern generation circuit 25 and the output signal of the selectionmeans 21 is selected in accordance with the copyright synchronizationpattern selection signal ST. That is, while the logic level of thecopyright synchronization pattern selection signal ST is “1”, the outputof the synchronization pattern generation circuit 25 is selected. Whilethe logic level of the copyright synchronization pattern selectionsignal ST is “0”, the output of the selection means 21 is selected.Therefore, a signal portion containing a synchronization pattern of“11011” appears periodically in the output of the data selector 24, andduring that period, a signal selected randomly by the selection means 21is contained.

In order to describe the output signal of the data selector 24, which isobtained in the above-described manner, in FIG. 5, the output (randomnumber value) of the random number generation means 22 is shown in FIG.5(I), and the output signal of the data selector 24 in a case where allthe values of 4-bit information b0 to b3 associated with the copyrightprotection information SA are assumed to be zero is shown in FIG. 5(J).In FIG. 5, signals shown in parts (A) to (H) are as described below.

-   -   (A)=>CK (channel clock)    -   (B)=>SY (initialization pulse)    -   (C)=>ST (copyright synchronization pattern selection signal)    -   (D)=>synchronization pattern signal    -   (E)=>M-sequence signal (M1)    -   (F)=>M-sequence signal (M2)    -   (G)=>M-sequence signal (M3)    -   (H)=>M-sequence signal (M4)

As is clear from FIG. 5, in the start 5-clock period by assuming therise time of SY and ST as a starting point, the logic level of thecopyright synchronization pattern selection signal ST is “1”, and thesynchronization pattern “11011” appears as it is as the output of thedata selector 24. However, from the sixth clock (CK), since the logiclevel of the copyright synchronization pattern selection signal STbecomes “0”, a signal which is irregularly changed, which is selected bythe selection means 21 in accordance with the output of the randomnumber generation means 22, is obtained.

For example, in the sixth clock, the output level of the random numbergeneration means 22 is “0”. In this case, since the selection means 21selects a sequence of M1, the data “0”, which is the same as that of thesixth clock of the sequence, is output from the selection means 21.Similarly, in the seventh clock, the output of the random numbergeneration means 22 is “3”. In this case, since the selection means 21selects a sequence of M4, the data “0”, which is the same as that of theseventh clock of the sequence, is output from the selection means 21. Inthis manner, when the output of the random number generation means 22 isdenoted as “j” (j=0, 1, 2, and 3), a sequence of Mk (k=j+1) is selected.Consequently, one of the four pseudo-random number sequences M1 to M4 isselected and output by the selection means 21. As a result, a signalsuch as that shown in FIG. 5(J) is obtained in the output of the dataselector 24.

FIGS. 5(K) and 5(L) show examples of outputs of the data selector 24 ina case where the output of the random number generation means 22 differsfrom that of FIG. 5(I). FIG. 5(K) shows a random-number sequence by therandom number generation means 22. FIG. 5(L) shows an output signal ofthe data selector 24.

It is assumed also in this example that all the values of the 4-bitinformation b0 to b3 of the copyright protection information SA are “0”.As described above, the M-sequence generation circuits 19A to 19D arerepeatedly reset periodically in accordance with the initializationpulse SY, and generate the same pseudo-random number sequences M1 to M4each time thereof. However, since the random number generation means 22is not reset even by the initialization pulse SY, in this example, arandom-number sequence (see FIG. 5(K)) completely differing from that ofFIG. 5(I) is output from the random number generation means 22. As aresult, even in the case of the same pseudo-random number sequences M1to M4, the selection result in the selection means 21 differs from thatof FIG. 5(J). That is, it is understood from a comparison between FIG.5(L) and FIG. 5(J) that a completely different signal waveform is formedexcluding the start 5-clock portion indicating the synchronizationpattern signal (“11011”).

The copyright protection information SA recorded in this manner isrecorded in such a manner that the probability of the positiondisplacement of the groove changes by a position relative to thesynchronization pattern. Therefore, by performing a computation suchthat the probability of the position displacement of the groove isdetermined in accordance with the position relative to thesynchronization pattern, the copyright protection information SA can bedetected (the details will be described later.).

The initialization of the M-sequence generation circuit is preferablyperformed in accordance with the address information of the disc at atiming at which the synchronization signal appears or at a timingdelayed with a particular fixed delay time from the time when thesynchronization signal appears. That is, in the address signal SZ, thesignal detecting synchronization signal is buried, and thissynchronization signal has no problem of secrecy and is recorded as asignal of a large amplitude (signal power) on the recording medium,making it easy to detect the signal during playback. Therefore, evenwhen a signal containing the copyright protection information issuperposed with a relatively small amplitude (signal power), the signalis not conspicuous much. Therefore, by detecting the synchronizationsignal contained in the address signal and by initializing the binarysequence using the appearance timing of the signal, this can be used toreconstruct and play back the copyright protection information. Ofcourse, in the application of the present invention, use is not limitedto only such an address signal, and, for example, signals containingvarious kinds of information, such as information unique to the discmanufacturing business owner, recommended conditions during discplayback (conditions for an automatic adjustment circuit of a player),and sound recording (image recording) capable time, can be used.

In FIG. 4, the output signal of the data selector 24 is supplied to oneof the input terminals of an analog multiplication circuit 26, and acarrier signal of a single frequency, which is generated by a carrier(carrier wave) generation circuit 27, is supplied to the other inputterminal of the analog multiplication circuit 26. That is, the analogmultiplication circuit 26 multiplies the output of the data selector 24by the output of the carrier generation circuit 27 in an analog manner,causing the high-frequency components of the signal output from the dataselector 24 to be shifted to higher frequencies, and the analogmultiplication circuit 26 outputs the result to a band-pass filter (BPF)28. The band-pass filter 28 allows only the output signal components ofthe data selector 24, which are shifted to higher frequencies by theanalog multiplication circuit 26, to be passed, thereby generating themodulation signal (copyright modulation signal) SX.

The analog multiplication circuit 26, the carrier generation circuit 27,and the band-pass filter 28 constitute modulation means 29 forgenerating a modulation signal in accordance with the integration signalfrom the data selector 24. The carrier frequency by the carriergeneration circuit 27 and the passing frequency band of the band-passfilter 28 are set so as to be different from the frequency band of theaddress signal SZ. As a result, frequency multiplexing of the copyrightmodulation signal SX and the address signal SZ becomes possible.

The copyright modulation signal SX obtained in the above-describedmanner is added together with the address signal SZ in the superpositionmeans 15 shown in FIG. 3, and thereafter, the signals are sent to theoptical modulator 9. The optical modulator 9 forms a wobble modulationmeans 30 for causing a track to wobble by performing radiation controlof a laser beam onto the optical master disc 200. In accordance with thecopyright modulation signal SX and the address signal SZ, the copyrightprotection information SA is recorded as a groove wobble on the opticalmaster disc 200 in a form which is not easily decrypted. In thisexample, since a recording form using a laser beam is adopted, themirror 10, the objective lens 11, and so on are required in addition tothe optical modulator 9. However, these optical components are notindispensable for the configuration of the wobble modulation means 30.In a form in which optical components are not necessary, for example, ina recording form in which electronic rays are used, wobble modulationmeans is formed by an electronic-ray modulator. That is, in this case,instead of the recording light source (laser light source) 8, anelectronic-ray generation source is used, and instead of the opticalmodulator 9, an electronic-ray modulator is used.

In the manner described above, in the present invention, signals basedon a plurality of sequences obtained by scrambling the digitalinformation by using a plurality of binary sequences are recorded on theoptical recording medium. That is, a plurality of signals generated ascomputation results using a plurality of random-number sequences arefinally collected as one signal. In the configuration of FIG. 4, onesequence is selected randomly from among a plurality of signalsequences. In this case, it is fine if the selection at each time isperformed in such a way that the sequence becomes accurately random.However, if the same sequence is selected for a long time, this isundesirable from the viewpoint of information secrecy. Therefore, asdescribed above, a random-number-like sequence is preferably used, andrandomness is preferably ensured also when a signal sequence isselected.

The signal which is finally obtained from among a plurality ofcomputation results is modulated and is subjected to necessaryprocessing, and thereafter, it is recorded on the recording medium. Asrecording means required therefor, in the above-described example, thedisc rotation control means 3, the optical radiation system 7, and thesignal processing section 12 are provided.

Then, in the case of the present invention, the copyright modulationsignal SX becomes a waveform which is different for each time withrespect to exactly the same copyright protection information SA. As aresult, the amount of the groove wobbling recorded on the disc becomesdifferent for each time.

A schematic representation of such a state of wobbling is shown in FIG.6. (However, in this figure, to conceptually facilitate understanding,it is shown assuming that the output of the data selector 24 is wobbledand recorded as it is. The wobbling of the grooves which are actuallyrecorded exhibits a more complex aspect since influences of the addresssignal SZ and the carrier are added).

As shown in the figure, in a copyright information recording area 2A ofthe disk-shaped optical recording medium 2, the copyright protectioninformation SA is recorded as a microscopic wobble pattern of a groovestarting from the synchronization pattern.

Furthermore, in the figure, the wobble pattern of each groove indicatesthe same copyright protection information SA regardless of the fact thatit is seen different for each track within the copyright informationrecording area 2A. That is, the recorded copyright protectioninformation SA is recorded as the wobble information of the groove insuch a manner that radiation control of a laser beam (or an electronicray) is performed using a modulation signal based on an integrationsignal such that the plurality of bit sequences and the plurality ofbinary sequences are integrated (the copyright protection information SAis recorded on the disc as a signal based on the data scrambled by arandom-number sequence). Therefore, even if the disc surface is observedusing an electronic microscope and a pattern corresponding to that ofFIG. 6 is confirmed, the meandering pattern of the recorded groove isgenerated randomly and cannot be easily decrypted. That is, by recordingthe copyright protection information SA on the disc by applying thepresent invention, since the information cannot be easily cracked, it ispossible to make the work of producing so-called pirated versions moredifficult.

The amount of information recorded on the copyright informationrecording area 2A needs to be determined by considering, for example,the conditions described below.

-   -   1. The number of recording bits of the copyright protection        information    -   2. The size of the signal amplitude (the larger the amplitude,        the shorter the recording interval is required. On the other        hand, if the signal amplitude is too large, a risk arises in        that the secrecy is degraded)    -   3. Variations in manufacturing of discs, and a scratch, etc.,        which occurs during handling after shipment    -   4. The length of one clock

Therefore, there are cases in which the amount of information for onetrack is sufficient, and it reaches several thousands or several tenthousands tracks.

In the example of the configuration shown in FIG. 4, in the integrationmeans 23, a random number or a pseudo-random number is generated, one ofthe plurality of computation results (the outputs of the digitalmultiplication circuits 20A to 20D) is selected in accordance with therandom number or the pseudo-random number, and this is output as theintegration signal. However, the integration means 23 is not limited tosuch a form. For example, as shown in FIG. 7, the construction may beformed in such a way that the integration signal is generated byproviding addition means for adding a plurality of computation resultsby the computation means 20.

In the example shown in FIG. 7, the differences from FIG. 4 are that anaddition circuit 31 is used as addition means in place of the selectionmeans 21 and the random number generation means 22 (therefore, of theportions shown in FIG. 7, the same reference numerals as those which arealready used are used for the portions which do not differ in thecomparison with the configuration shown in FIG. 4, and accordingly,descriptions thereof are omitted.).

The outputs of the digital multiplication circuits 20A to 20D are inputto the addition circuit 31, and the addition circuit 31 sends the outputobtained by adding them to the data selector 24 at a subsequent stage.

Therefore, in the data selector 24, one of the synchronization patternand the output of the addition circuit 31 is selected in accordance withthe copyright synchronization pattern selection signal ST, and theselection result is sent to the analog multiplication circuit 26 of themodulation means 29.

In this example, since the addition result by the addition circuit 31 isa multi-valued signal, a process for recording and playing back themulti-valued signal is necessary. When the multi-valued signal is used,the generated signal becomes often more smooth than that of the formusing a binary signal, and the secrecy can be increased with regard tothe copyright protection information hidden by superposition with theaddress signal.

A description will now be given below of an information processingapparatus for recording or playing back information by using an opticalrecording medium in which the copyright protection information SA isrecorded. Examples of the apparatus include a disc information playbackapparatus or recording apparatus, and an apparatus for recording andplaying back disc information.

FIG. 8 is a schematic illustration of a system associated with recordingand playback.

The copyright protection information SA is recorded in the copyrightinformation recording area 2A of the optical recording medium 2 by usingthe information recording apparatus 1 (in this example, an opticalrecording apparatus).

During the data playback in the information processing apparatus, acorrelation computation is performed between the signal of a sequenceand a played back signal by using a plurality of binary sequences, whichare the same as those used to scramble information when the copyrightprotection information SA is recorded, reconstructing the copyrightprotection information SA (decrypted). Since a secrecy process byencryption is performed on the played back signal by using the SA, theencryption which is performed during recording is unscrambled by usingthe decrypted copyright protection information SA, the original playedback data is obtained.

During the data recording in the information processing apparatus, afterrecording data (user data) is encrypted using the copyright protectioninformation SA, a process for recording onto the recording medium isperformed after undergoing a modulation process suitable for recordingonto the optical recording medium 2.

FIG. 9 shows an example of the configuration of an optical discrecording and playback apparatus for performing information recordingand information playback onto an optical disc in which the copyrightprotection information SA and the address signal SZ are recorded.

On the optical recording medium 2 used in an information processingapparatus 32, as described above, signals based on a plurality ofsequences obtained by scrambling the copyright protection information byusing a plurality of binary sequences are recorded. Then, thedisk-shaped optical recording medium 2 is rotated by a spindle motor,which is a driving source 33. The spindle motor is controlled inaccordance with a signal from a servo circuit 34.

An optical pickup (or an optical head) 35 is controlled (tracking servocontrol and focusing servo control associated with objective lensdriving, or sled control for changing the field of view position) so asto perform a predetermined operation by the optical pickup 35. A signalgenerated by the optical pickup 35 is sent to a matrix amplifier 36,where the signal is converted into a track error (or a tracking error)signal “TK”, a focusing error signal “FS”, a push-pull signal “PP”, anda magneto-optical detection signal “MO”. The track error signal “TK” andthe focusing error signal “FS” are supplied to the servo circuit 34,where the signals are used for focus positioning control and trackingcontrol associated with the objective lens of the optical pickup 35.Furthermore, the push-pull signal “PP” is a signal of the difference inthe amounts of light (so-called radial push-pull signals) by a detectorhaving two portions and is supplied to an A/D converter (analog/digitalconverter) 37, where the signal is used to detect the copyrightprotection information SA and the address information. Since thesepieces of information are recorded as groove wobbles on the disc, awobble signal can be generated by detecting the groove wobble. That is,the optical pickup 35 and the matrix amplifier 36 constitute wobbledetection means 38.

The MO signal obtained in the matrix amplifier 36 is supplied to adecryption circuit 39, where user data recorded as a magneto-opticalsignal is decrypted. The decryption circuit 39 performs EFM (Eight toFourteenth Modulation) demodulation from the supplied MO signal. TheEFM-demodulated data is sent to an encryption unscrambling circuit 40.This encryption unscrambling circuit 40, together with a CPU (to bedescribed later), constitutes encryption unscrambling means forunscrambling the encryption performed on the recorded information of theoptical recording medium 2 so as to reconstruct the information. In thiscircuit, the information whose encryption based on the copyrightprotection information SA is unscrambled is supplied as signals in unitsof 8 bits to an ECC circuit 41.

The ECC circuit 41 corrects a code error contained in the output signalof the encryption unscrambling circuit 40 in accordance with the ECC(Error Correction Code) added in the coding during the recorded. Sucherrors are caused to occur by, for example, defects on the disc.

During the recording of data, the input user data is sent to anencryption circuit 43 through an ECC circuit 42. The encryption circuit43, together with a CPU (to be described later), constitutes encryptionmeans for encrypting recording information and for recording it onto theoptical recording medium 2. In this circuit, data on which an encryptionprocess based on the copyright protection information SA is performed issent to a modulation circuit 44, where the data is modulated (issubjected to EFM). Then, the data is sent to the matrix amplifier 36,where a process for recording it on the disc is performed.

The data which is digitized by the A/D converter 37 is sent to a seconddecryption circuit 45, where a decryption process is performed on thedata, and the copyright protection information SA obtained thereby issent to a CPU (Central Processing Unit) 46. In order that the decryptedSA does not leak outside, care is necessary such that the SA is managedonly within the integrated circuit such as an LSI, and such that, whenthe SA is to be transferred to the outside, it is transferred aftermutual authentication is performed and a secrecy process such asencryption is performed.

A description will now be given of a case in which the copyrightprotection information SA is detected from the recorded information ofthe copyright information recording area 2A (see FIG. 6) on the disc.First, the CPU 46 gives instructions to the optical pickup 35, and in astate in which focusing servo and tracking servo associated with thedriving of the objective lens are activated, the copyright informationrecording area 2A in the inner region of the disc is accessed. At thistime, the copyright modulation signal SX and the address signal SZ,which are recorded as groove wobbles, are observed as the push-pullsignal “PP”.

In the A/D converter 37, the push-pull signal PP is converted into an8-bit digital push-pull signal (denoted as “DX”) in accordance with aclock (not shown), and this signal is supplied to the second decryptioncircuit 45. The second decryption circuit 45 decrypts the copyrightprotection information SA from the digital push-pull signal DX (thedetails will be described later), and outputs it to the CPU 46.

The CPU 46 outputs the copyright protection information SA supplied fromthe second decryption circuit 45 to the encryption unscrambling circuit40. As described above, the encryption unscrambling circuit 40unscrambles the encryption of the signals supplied from the decryptioncircuit 39 in accordance with the copyright protection information SAsupplied from the CPU 46, and supplies them as signals in units of 8bits to the ECC circuit 41.

In the disc on which the copyright protection information SA iscorrectly recorded in this manner, it is possible for the user to enjoythe music information recorded on the disc as a result of the encryptionbeing correctly unscrambled in the encryption unscrambling circuit 40.On the other hand, on a disc on which the copyright protectioninformation SA is not correctly recorded (an illegally copied disc,etc.), since the encryption unscrambling circuit 40 does not correctlyoperate, it is not possible for the user to enjoy the music informationrecorded on the disc. In this manner, on the disc on which the copyrightprotection information SA is not correctly recorded, since musicplayback is not performed, for example, the value of a pirated disc canbe decreased considerably, and the widespread use of illegally copieddiscs can be prevented (as a result, the profits of copyright owners canbe protected).

Furthermore, in the information processing apparatus 32, when the usernewly records data on a disc, first, the ECC circuit 42 adds an errorcorrection code to the input user data. After that, in the encryptioncircuit 43, encryption is performed in accordance with the copyrightprotection information SA from the CPU 46, and the modulation circuit 44performs modulation such as EFM, and thereafter, sends the output to thematrix amplifier 36. Then, by using the optical pickup 35, informationis recorded as a magnetic pattern on the disc by the magnetic head alongwith the radiation of a laser beam.

With regard to the user data recorded on the disc in this manner, anencryption process is always performed in accordance with the copyrightprotection information SA unique to the disc. Therefore, even if theuser data on the disc is copied by improper means and is distributed aspirated discs, since the copyright protection information SA used as akey (encryption key) during encryption cannot be played back from thepirated disc, the encryption applied to the user data which is illegallycopied on the pirated disc cannot be unscrambled. As a result, since thevalue of the pirated disc can be lowered considerably, the widespreaduse of pirated discs can be prevented, and as a result, the profits ofcopyright owners can be protected.

Next, the second decryption circuit 45 will be described.

FIG. 10 is a block diagram showing an example of the configuration ofthe second decryption circuit.

As described above, the decryption of the copyright protectioninformation SA is performed in accordance with the signal from thewobble detection means 38. In this example, the wobble detection means38 is a push-pull detection means for detecting a push-pull signal (PP).The push-pull signal PP is sent from the matrix amplifier 36 to the A/Dconverter 37, where the push-pull signal PP is converted into a digitalpush-pull signal DX.

Then, this digital push-pull signal DX is input to a low-pass filter(LPF) 47 and a band-pass filter (BPF) 48.

The low-pass filter 47 is provided to extract and output the componentsof the address signal SZ by allowing only the low frequency componentscontained in the digital push-pull signal DX to be passed. Furthermore,the band-pass filter 48 extracts and outputs the components of thecopyright modulation signal SX by extracting only the signal of the highfrequency components contained in the digital push-pull signal DX.

The output of the low-pass filter 47 is sent to a PLL (phase-lockedloop) circuit 49 and a synchronization detection circuit 50. The PLLcircuit 49 plays back a clock synchronized with the address signal SZ,thereby producing and outputting the channel clock CK, which is the sameas that used during recording, and supplies it to the sections of thesecond decryption circuit 45.

The synchronization detection circuit 50 is a circuit provided to detecta synchronization timing from the wobble signal. The synchronizationdetection circuit 50, together with the low-pass filter 47, constitutessynchronization detection means 51. That is, the synchronizationdetection circuit 50 detects the synchronization signal componentscontained in the address signal SZ, and outputs the initialization pulseSY at the same timing as that used during recording. That is, in thisexample, the synchronization detection means 51 is address detectionmeans for detecting address information.

The initialization pulse SY is a pulse such that the logic level becomes“1” for a period of one clock, and it is output at the same timing asthat shown in FIG. 5(B). That is, regarding the initialization timing,since the channel clock CK is reproduced by the PLL circuit 49 in thesame way as during the recording, the timing can be measured by countingthe CK by a predetermined number after the synchronization signal isdetected.

Reconstruction means 52 for reconstructing the copyright protectioninformation SA includes binary-sequence generation means 53, computationmeans 54, and decryption means 57.

M-sequence generation circuits 53A to 53D constitute the binary-sequencegeneration means 53 for generating a binary sequence in accordance withthe synchronization timing based on the initialization pulse SY. Thatis, the M-sequence generation circuits 53A to 53D are initialized by theinitialization pulse SY, generate pseudo-random number sequences M1 toM4 formed by M sequences, which are identical to those used in (themodulation means 13 of) the above-described information recordingapparatus 1, and output them to digital multiplication circuits 54A to54D correspondingly.

The digital multiplication circuits 54A to 54D constitute thecomputation means 54 for digitally multiplying the data of thepseudo-random number sequences M1 to M4 by the output data (SX) of theband-pass filter 48. That is, when the logic level of the pseudo-randomnumber sequence M1 is “1”, the digital multiplication circuit 54Ainverts the polarity of the signal SX and outputs this signal to adigital integration circuit 55A. Furthermore, when the logic level ofthe pseudo-random number sequence M1 is “0”, the digital multiplicationcircuit 54A outputs the signal SX as it is to the digital integrationcircuit 55A. That is, in the same way as during recording, a computationof exclusive OR (or logical NOT thereof) is performed.

The other digital multiplication circuits 54B to 54D perform the samecomputations as that of the digital multiplication circuit 54A withrespect to the pseudo-random number sequences M2 to M4 and the output ofthe band-pass filter 48, and output the results to the digitalintegration circuits 55B to 55D (that is, assuming that “x=B, C, or D”,the computation result of the M-sequence generation circuit 53 x and thedigital multiplication circuit 54 x associated with each output of theBPF 48 is output to the digital integration circuit 55 x.).

The digital integration circuits 55A to 55D forming the decryption means57 integrate the values obtained as the computation results in thedigital multiplication circuits 54A to 54D one after another, so that acomputation for determining the probability of the groove positiondisplacement in accordance with the relative position from thesynchronization pattern is performed. As a result of performingintegration in this manner, it is possible to reconstruct theinformation recorded as the copyright protection information SA byremoving the influence of the random number used during the recording.

That is, in this example, the degree of correlation between the playedback signal of the disc and each carrier signal (a plurality ofbinary-sequence signals). If components of a particular carrier (binarysequence) are contained as positive polarity in the played back signal,the degree of correlation indicates a large positive value. Furthermore,if the binary sequence is contained as the negative polarity (0 and 1are inverted) in the played back signal, the degree of correlationindicates a large negative value. This makes it possible to determine asto whether “1” is recorded in each bit or “0” is recorded in each bit.

When the plurality of binary sequences recorded on the disc are in anorthogonal relationship, that is, when the cross-correlation is in azero relation, even if components of a plurality of binary sequences aresuperposed in the played back signal, by determining the degree ofcorrelation between the played back signal and an arbitrarybinary-sequence signal, only the intensity (polarity) of the desiredbinary-sequence components can be known by eliminating the influence ofthe other binary-sequence components. As described above, thereconstruction means 52 is none other than means for determining thedegree of correlation between a plurality of binary sequences and theplayed back signal. Regarding the method for determining the degree ofcorrelation, for example, in the case of an analog signal process, whiletwo signals are being multiplied, the result may be integrated.Furthermore, as in this example, in the case of a binary signal, insteadof multiplication, exclusive OR or reverse logic (NOT logic) thereof maybe used.

The integration results in the digital integration circuits 55A to 55Dare supplied to digital determination circuits 56A and 56D,respectively. The digital determination circuits 56A and 56D compare theinput signal with a predetermined threshold value, therebyreconstructing and outputting the bits b0 to b3 of the copyrightprotection information SA. The digital multiplication circuits 54A to54D and the digital integration circuits 55A to 55D are circuits fordetermining a correlation value (or a correlation coefficient) betweenthe signal SX based on the played back signal from the disc and eachcarrier signal (a plurality of binary-sequence signals). Eachcorrelation value takes a positive or negative value depending on thelogic value of each bit. Therefore, the “predetermined threshold value”in the digital determination circuits 56A and 56D is zero (or at a zerolevel) in this case.

In the manner described above, in the decryption means 57, byintegrating the wobble signal while performing a computation with aplurality of binary sequences M1 to M4, each bit of the copyrightprotection information SA is decrypted. That is, a plurality ofintegration means 55 for integrating each of the computation results ofa plurality of different binary sequences and the wobble signal areprovided, and by concurrently performing detection for each bitassociated with the copyright protection information SA, decryption foreach bit is performed.

In this manner, in this configuration, the clock used during therecording and four pseudo-random number sequences M1 to M4 arereproduced by using the synchronization pattern inserted into theaddress signal SZ, and the correlation integration between these and theplayed back signal (push-pull signal) detected from the optical pickup35 is performed, making it possible to reconstruct the copyrightprotection information SA recorded on the disc.

The fact that the influence of a random number used during the recordingcan be removed by detection using integration has already been stated.Even in a case where a portion of a played back signal is lost due todefects which occur in disc manufacturing steps, or a scratch on thesurface of the disc, which occur during handling of the disc, it ispossible to reliably detect the copyright protection information SA byrepeatedly performing integration computations.

In the above-described example of the configuration, a synchronizationpattern buried in the address signal SZ is used to reproduce theinitialization pulse SY. Alternatively, since the copyrightsynchronization signal is also buried in the copyright modulation signalSX, the signal can also be used. That is, in another configurationexample, associated with the synchronization detection means 51, asindicated by the broken line in FIG. 10, the copyright synchronizationsignal contained in the output of the band-pass filter 48 may bedetected, and the initialization pulse SY may be reproduced insynchronization with this detection. In this case, the output terminalof the band-pass filter 48 is connected to the synchronization detectioncircuit 50, and in the groove wobble recorded on the disc, theinitialization pulse SY can be reproduced by detecting the fact that thesynchronization pattern “11011” is repeatedly recorded at apredetermined period.

According to the above-described information processing apparatus 32,effective copyright protection can be realized by preventing illegalcopying operation by control associated with encryption of user data orencryption unscrambling thereof, in which playback of the copyrightprotection information SA is possible and the copyright protectioninformation SA is used as a key.

Industrial Applicability

As is clear from the foregoing, according to the present invention, thecopyright protection information is not easily found out as long as theplurality of binary sequences used for scrambling are not known.Therefore, the profits of copyright owners can be effectively protected.

According to the present invention, by recording signals based oncopyright protection information as wobble information associated withthe optical recording medium, the secrecy of information can beincreased.

1. An information recording apparatus for recording digital informationfor protecting copyright by radiation of light or by radiation ofelectronic rays onto a recording medium, wherein a signal based on aplurality of sequences obtained by scrambling said digital informationby using a plurality of binary sequences is recorded on the recordingmedium.
 2. An information recording apparatus according to claim 1,comprising: binary-sequence generation means for generating a pluralityof binary sequences at a timing based on synchronization detection;computation means for outputting a computation result of a plurality ofbits associated with said digital information, and said plurality ofbinary sequences; integration means for integrating a plurality ofcomputation results obtained by said computation means in order togenerate an integration signal; modulation means for generating amodulation signal in accordance with said integration signal; and wobblemodulation means for making a track wobble by performing radiationcontrol of a laser beam or an electronic ray onto the optical recordingmedium in accordance with said modulation signal.
 3. An informationrecording apparatus according to claim 1, wherein said binary sequenceis an M sequence.
 4. An information recording apparatus according toclaim 2, wherein said binary sequence is an M sequence.
 5. Aninformation recording apparatus according to claim 2, wherein saidintegration means comprises random number generation means forgenerating a random number or a pseudo-random number, and selectionmeans for selecting and outputting one of said plurality of computationresults in accordance with the random number or the pseudo-random numberfrom the random number generation means.
 6. An information recordingapparatus according to claim 2, wherein said integration means generatessaid integration signal by adding a plurality of computation results bysaid computation means.
 7. An information recording apparatus accordingto claim 2, wherein said computation means performs an exclusive ORcomputation of said digital information and said plurality of binarysequences.
 8. An information recording apparatus according to claim 2,comprising: an information source for generating second digitalinformation; second modulation means for generating a second modulationsignal in accordance with said second digital information; andsuperposition means for superposing a first modulation signal obtainedby said modulation means and said second modulation signal, wherein saidwobble modulation means performs wobbling under said radiation controlof a laser beam or an electronic ray in accordance with the output ofsaid superposition means.
 9. An information recording apparatusaccording to claim 8, wherein said plurality of binary sequences areinitialized at a timing based on a synchronization signal in said secondmodulation signal.
 10. An information recording apparatus according toclaim 8, wherein said superposition means adds the first modulationsignal and the second modulation signal after the frequency componentsof said first modulation signal, said second modulation signal, or thetwo modulation signals are adjusted, thereby causing the two modulationsignals to be frequency multiplexed.
 11. An information recordingapparatus according to claim 8, wherein said second digital informationis address information used to access said optical recording medium. 12.An information recording method for recording digital information forprotecting copyright by radiation of light or by radiation of anelectronic ray onto a recording medium, said information recordingmethod comprising: a step of scrambling said digital information byusing a plurality of binary sequences; and a step of recording, on therecording medium, a signal based on a plurality of sequences obtained bythe scrambling.
 13. An information recording method according to claim12, comprising the steps of: determining, after a plurality of binarysequences are generated at a timing based on synchronization detection,a plurality of computation results by a computation of a plurality ofbits associated with said first digital information and said pluralityof binary sequences; integrating said plurality of computation resultsas an integration signal, and thereafter generating a modulation signalin accordance with the integration signal; and making a track wobble byperforming radiation control of a laser beam or an electronic ray ontoan optical recording medium in accordance with said modulation signal.14. An information recording method according to claim 12, wherein an Msequence is used as said binary sequence.
 15. An information recordingmethod according to claim 13, wherein an M sequence is used as saidbinary sequence.
 16. An information recording method according to claim13, wherein a random number or a pseudo-random number is generated, andone of said plurality of computation results is selected in accordancewith the random number or the pseudo-random number and is used as anintegration signal.
 17. An information recording method according toclaim 13, wherein said integration signal is generated by adding saidplurality of computation results.
 18. An information recording methodaccording to claim 13, wherein a computation result is determined byperforming an exclusive OR computation of said digital information andsaid plurality of binary sequences.
 19. An information recording methodaccording to claim 13, wherein second digital information is generated,and wobbling is performed by said radiation control of a laser beam oran electronic ray in accordance with a signal such that a secondmodulation signal based on the second digital information and themodulation signal based on said integration signal are superposed. 20.An information recording method according to claim 19, wherein saidplurality of binary sequences are initialized at a timing based on asynchronization signal in said second modulation signal.
 21. Aninformation recording method according to claim 19, wherein the firstmodulation signal and the second modulation signal are frequencymultiplexed by adding the first modulation signal and the secondmodulation signal after the frequency components of said firstmodulation signal, said second modulation signal, or the two modulationsignals are adjusted.
 22. An information recording method according toclaim 19, wherein address information used to access said opticalrecording medium is used as said second digital information.
 23. Anoptical recording medium having recorded thereon digital information forprotecting copyright, wherein a signal based on a plurality of sequencesobtained by scrambling said digital information by using plurality ofbinary sequences is recorded.
 24. An optical recording medium accordingto claim 23, wherein said digital information is recorded as wobbleinformation of a groove by performing radiation control of a laser beamor an electronic ray by using a modulation signal based on anintegration signal such that computation results of a plurality ofbinary sequences and a plurality of bits associated with said digitalinformation are integrated.
 25. An optical recording medium according toclaim 23, wherein said plurality of binary sequences are M sequences.26. An optical recording medium according to claim 24, wherein saidintegration signal is a signal which is integrated by selecting andadopting said plurality of computation results in accordance with arandom number or pseudo-random number sequence.
 27. An optical recordingmedium according to claim 24, wherein said integration signal is amulti-valued signal such that said plurality of computation results areadded.
 28. An optical recording medium according to claim 23, whereininformation encrypted using said digital information is recorded.
 29. Anoptical recording medium according to claim 24, wherein a secondmodulation signal obtained by modulating second digital information issuperposed onto a modulation signal based on said integration signal,and the signal, together with said digital information for protectingcopyright, is recorded as said wobble information of a groove.
 30. Anoptical recording medium according to claim 29, wherein said secondmodulation signal is superposed onto a modulation signal based on saidintegration signal by frequency multiplexing.
 31. An optical recordingmedium according to claim 29, wherein said second digital information isaddress information used for accessing data.
 32. An informationprocessing apparatus for recording or playing back information by usingan optical recording medium having recorded thereon digital informationfor protecting copyright, wherein said digital information isreconstructed by performing correlation computation between a binarysequence and a played back signal associated with said optical recordingmedium by using a plurality of binary sequences, which are the same asthose used to scramble the information when said digital information isrecorded.
 33. An information processing apparatus that uses an opticalrecording medium in which digital information for protecting copyrightis recorded as a wobble of a groove and that records or plays backinformation by radiating a laser beam or an electronic ray onto theoptical recording medium according to claim 32, said informationprocessing apparatus comprising: wobble detection means for detectingsaid groove wobble in order to generate a wobble signal; synchronizationdetection means for detecting a synchronization timing from said wobblesignal; binary-sequence generation means for generating a binarysequence in accordance with said synchronization timing; and decryptionmeans for decrypting said digital information by integrating said wobblesignal while performing a computation with said binary sequence.
 34. Aninformation processing apparatus according to claim 32, wherein saidplurality of binary sequences are M sequences.
 35. An informationprocessing apparatus according to claim 33, wherein said wobbledetection means is push-pull detection means for detecting a push-pullsignal.
 36. An information processing apparatus according to claim 33,wherein said synchronization detection means is address detection meansfor detecting address information used to access an optical recordingmedium.
 37. An information processing apparatus according to claim 33,comprising: a plurality of integration means for integrating each ofcomputation results of the exclusive OR of a plurality of binarysequences, which are generated by said plurality of binary-sequencegeneration means and which differ for each other, and said wobblesignal, wherein a plurality of bits associated with said digitalinformation are detected concurrently.
 38. An information processingapparatus according to claim 32, comprising: encryption means forencrypting and recording information to be recorded on said opticalrecording medium by using said digital information.
 39. An informationprocessing apparatus according to claim 32, comprising: encryptionunscrambling means for unscrambling encryption performed on therecording information of said optical recording medium by using saiddigital information.